Roasting furnace



June 16, 1925. A I 1,542,150

A. V. LEGGO ROASTING FURNACE qiginal Filed Deo, 2z. 1921 sweets-sheet 1 .f -L Q 1, mmpmmw' June 16, 1925. V 1,542,150 A. v. LEGGO HOASTING FURNACE` original Filed Dec, 22'. 1921 :5 sheets-Sheet `s .I www @mami by w' m Patented June 16, 1925.

; unirse .TES

era-nnen virer-cannes@ or MELBOURNE," morente,"ausnahme, y

noasrrne rotting;n.'`

`mechanisifn used `in such furnaces. This application is a divisi-on olimy prior application lilo. 524,301, filed December E22, 1921.

lt is well lniownfthat the iabbling` mechanism of a furnace being` subject to great wear and tear reqniresmore or less repair or replacei'nent and attention to maintain its eliciency andas the furnace must be stopped dining the time `siich repair-sor replacements are being made, and as any break in the continuity ofi operations causes changes iny ten'iperature andV in conditions which prejudice the eliiciency ot- `metalll'irgical operations,` `the more as the said "changes are greater, it isoit the utmost importance to reduce the time of making ad- `ji:stmcnts and" repairs to a minimum.

'.lhe thorough exposure ot the material under treatment tothe furnace gases and eren distribution o' lthe same over the rabble paths, especially if large tonnages are handled,have hitherto presented diliculties which have only beenln'iin-imiz-cd by means ol" costly and complicated-arrangements of the rabbling r eehanism. lVl'oreoveigthe loss ot' capacity or a furnace during a prolonged stop 'for replacement of any part et the rabblingl mechanism and duringthel period required alter a longfst-op for theiurnace to retlnnfto` normal conditions militates to a great degree against economical working. The period required." for replacement olf broken orworn parts is often prolonged by the iact that under the extremely arduous conditions imposed by mofdernnrnace practise the said parts become distorted and diiiicnlt to remore yfrom-fthe `fiirnavce when replacement becomes 1recessary5-thisf bei-ng more. pronounced-as the complication of the rabbling mechanism lis increased. Y

'lhe present invention provides certain improvements in the rabbling mechanism of multiple hearth roasting fn-rna'cesto -liaciliaccess to every part of the rabbling` mechanism whereby renewals and repairsy partly .in section.,

therein can be eli'ected in a minimum et' tlme andJ whereby thev 4disadvantages Vincidental to the cooling` down of the furnace are minimized and`wliereby are effected `greater eieiency;q economy and flexibility than hare been possible heretobefore in roasting operations.r

The improvements' comprised in the present invention more particularly consist in the provision of simple and eiiicient means `for detaehably connecting-the rabble 'arms tothe rabble `sha'lf'ts whereby a water or air-tight joint is el'lected between the rabble arms and shafts-so that the arms can be easily attachedyto and detached 'from the rabble shafts when working 'from the ontside and from one side only of a `furnace and in the provision of meansffor control- .ling the passage of a cooling medium through the rabble shafts and arms.`

In order that the linvention may` be readily understood@reference willlnow be Vhad to the accompanying sheets of explana- "ydrawings whereinuw y Y Figure l .is a Iview insectional,elevation of part of a straight line nniltiple hearth furnace showing-a rabbleshalit with arms attached constructed in accordance with the 1in-osent inrention.`

In `this View the mechanism for efectin the rotation of the rabble o. C shafts 1s shown located* above. the furnace.

Figure 2 is a View in sectional elevation of a rabble shaft and arms and shows means for introducing a cooling medium (more particularly water) thereto. Y

Fig. 2a. is a .ir'agiiientary side elevation, Y l showing the use of a fan in a nio-dilied form.l f

Figure 3 is a View in sectional plan of a rabble shaft and arm, and shows clearly the means for connecting` the lone to the other te form a water or air-tightjoint. In this View a portion of the rabble arm is shown broken away for convenience of illustration.

Figiire'l is a View in sectional elevation of part ot a rabble shaft andparts of rabble arms taken on theV dotted line a-llu of Figure 3.

Figure 5 is a View in sectional plano'f a rabble shaft and portion ofa rabble arm showing a slight modification in 4themeans employed for connecting the one to the other. i

Figure (3 is a View in sectional eleyation original @paca-aon ined December se, leerse-iai nare-4,301. minded ma uns application inea July a,

f 1923-. semi no; Grassi.

taken on the dotted line (561 of Figure 5.

Figure 7 is a view in perspective of part of the rabble shaft and the inner end of the rabble arm illustrated in Figure 3 showing clearly the construction of the same at the part to form a joint.

Figure 8 is a view in sectional plan of a solid rabble ar n adapted to be connected to a rabble shaft by means of the joint shown in Figure 7. y

Figure 9 is a view in sectional end elevation of the rabble arm shown in Figure 8 and taken on the dotted line Srl-9a.

Figure l0 is a view in end elevation of the rabble arm shown in Figure 8.

In these drawings the numeral 13 designates a rabble shaft which is supported at its lower end in a footstep bearing and is driven in any approved way.

The hollow rabble shaft passes through the centre of the 'furnace and has its lower end supported adjustably in a footstep bearing 23 located below the furnace. Portion only of a multiple hearth furnace is shown in Figure l and is designated by the numeral l.

lf cooling is effected by circulation of air it is more convenient to place the driving gear below the lowest hearth and to withdraw the heated air from the top of the rabble shafts by suction produced by any well known means. j

The rabble shafts 13 are made hollow and cooled by water or air and at a point above each hearth the rabble shafts are fitted with detachable rabble arms 36 which also are made hollow when a cooling medium is employed, and solid when the circulation of a cooling medium therethrough is not required.

The rabble arms are arranged alternately on opposite sides of the rabble shafts as shown in Figures l and 4 and at points above each hearth the sides of the shafts are formed with outwardly flared sockets 37 into which tit correspondingly shaped spigots 38 formed on the inner ends of the rabble arms (see Figures 8 and 4).

The butt end of the rabble arm on both sides of the spigot, is formed with jaws 39 which are adapted to eno'age and slide freely in recesses 40 formed lhorizontally in the sides of the rabble shaft (see Figures 9. and 7).

The recesses 40 in the sides of the rabble shaft are parallel to the axes of the sockets and are shaped to accommodate and form guides for the jaws 39 thereby enabling the spigots to be easily and correctly introduced into the sockets when working through observation holes in one or both sides of the furnace.

Then the aws 39 on the rabble arms are placed in engagement with the recesses 4() on the sides of the shafts, gibs 4l and cotters 42 are inserted into slots 43 formed horizontally in the outer end of the said jaws.

The cotters and gibs are adapted to bear against the rabble shaft and the backs of the slots, respectively, and when the cotters are driven into place they will draw the tapered spigots tightly into the tapered sockets and thereby form a water or airtight joint between the rabble arms and shaft.

The intertitting conical faces of the spigots and sockets are made to template so that when the former are introduced into the latter and drawn inwardly by tightening the cotters, the said conical faces will bear hard against each other and their nicety of fit ensures a perfectly water-tight joint.

The conical faces are the only parts of the joint which bear against each other and therefore the tighter the cotters are driven, the more the spigot is drawn into the socket and the greater is the pressure between the said faces.

ln the modified forni of the joint shown in Figures 5 and G of the drawings a spigot 44 is formed on the side of the shaft so as not to project beyond or only slightly beyond the circumference thereof or any protective covering thereon and the entrance to the hollow rabble arm is flared to form a tapered socket 45 which is adapted to lit neatly over the said spigot on the shaft. The joint shown in Figures 5 and 6 provides a maximum amount of opening from the shaft to the arm and consequently ensures ample free dom for the circulation of cooling medium from one to the other. Moreover this forni of joint is such that the shaft is not unduly weakenedat the point of greatest load by having in it a large opening for the attachment of the arm, thus enabling a smaller and cheaper shaft to do the work eliciently.

Apart from those constructional details consequent upon reversal of the socket and spigot the joint is constructed as shown in and described with relation to Figures 3 and 4 of the drawings.

The passages through the hollow rabble shafts are somewhat restricted at the points 46 where the arms are connected thereto in order to compensate for the reduction of metal due to the formation of the guide recesses 40 and the sockets 37 and spigots 44 and to provide a sufficient body of metal at these points to ensure a requisite amount of strength.

The recesses 40 in the sides of the rabble shafts engage the jaws on the arms more or less neatly so as to ensure the arms being supported in or approximately in their normal horizontal positions without necessitating any other support, thereby enabling 1,254,251 iso the mittel-sand gibst() be'easilyhandiqnickly `placed in position when asseinbiingftheiparts.

j A horizontal recess 148. -(Figureit) or shoulder 49 (Figuref') 4is torinedon *the rabble shaitlj ust aboiie'- the axis oteach joint iiiid on `tho opposite -side ot-'tlie said -sha'tt to tthat on which-'the said joint is i` located.

livheii the cotterslilQ aredriveninto position j' they are adapted toibeiaragainstthe upper iiialls oit the recesses i8 oimagainstftheshoulders 49" thereby ensuring Vthe rabble iarins being maintained horizontally. 1llffthe kposition ot `the cottcris such ithat it does'not Abearagainst the topolfthereeess #i8 orshoulject troni` opposite `sidesy thereot or they i can be arrangedttogproject froni inorethan two sides oifrtli'esha'iit or in any other approved way. f i j j Y' j The hollow rabble Aarnis` and'shatts can be `'lorined withoiit-central partitions -as shown in Figure or they can be forined withpar` titions' shown clearly in EFigiire-s2 and 5 ot the drawings. j Y

then the hollow i rabble' arins 36 are 'l'oriiied `withcentral `Vertical partitions 50 "the said partitions extend from theinnei" lends near to theouteraends of the-Said arnis 'and t-lierinner endsiot the said partitions are adapted to abntinore orf'less neatly against central Vertical partitionsilfinthe rabble shafts whenthearms-aie secured in position thereto. j

Inorder to ensiire fa i water tight or an apjrsroriinately `water tight joint betiifeenthe partition 50 in the rabble arin and the parti tion lil'in the shalt, afiilling piece 52 of suitable material is interposed between the adjacent edges of the said partitions. This filling piece will ensure a satisfactory joint when the spigot and socket connections will not periiiit of sutiicient take up to allow ot the said partitions abutting close enough to eitiect a satisfactory circulation of a oooling inediuin through the shaft and ariiis.

The lilling piece prevents the cooling` nie-V diiiin short circuiting through the gap between the adjacent parts of the partitions and ensures the said cooling` inediuni being directed to the end ot the rabble ai'in. The tilling piece in no way assists in forni-i ing; a water-tight joint liietween the ariii and.

Vthe shaft and even it it does not conipletely till the gap it will be more or less effectual `the ariiiitand the purin directing'thc cooling farins. i j

The `abnttingedgesot the partitions 50 and l' canbe made plain. or theycan be `shaped as vshown in lhligure of the drawings to riiiediuin into *the `more eftlleetirally `preventthe short circuitilng" o'lwtheooolinp' iifiediuin in its passage troni the shaft-to theniarins.

The vertical partition 5l ofthe rabble vshaft"entends nearly the lull length thereof and the'ends are turned iii opposite directions at 53 and unite with .opposite sides of the interior ot the rabble shaft.

The partition inthe rabble shaft divides 'the interior.thereof into two separate vein `tical.chambers and 55 so that when a cooling` inediiiin isdelirered troni a supply pipe 556i to thenpper end ot tliechainber Si, it will tlow thereitroin along one side of' `the the ,the

partition 50 in a rabble ai'in and back other side of the said partition into second chamber '55 inthe rabble sli-att and `thence Ito an overflow 57 `provided torithe diseharge thereof (see Figure);

rlhe ineaiis hereinheore described for oonnetting` the a'riiis to the shaft so as to ineke yan :eliiectia'efjoiiit therebetween iseqiially ap- `plficableiin thosecases where theshatt and ariiis are notpi'ovided with `partitions for governing` the oiroulationof .acooling ine? `diuin therethrough which :may then be `passed intotheshaiit through a .pipe 5T.

The pipei depends within the shaft to a point below the bottoni arin therconand the coolingl niediuin'passes troni-.the lower `entl of the said pipe and in ascending` the shaftiit oiroulates.through thcgarnis attached tlieieto.(see Figures 3 and et).

lVhen thesharft andni'ins arcooolediby airltheair isdraiif'n' `troni the upper end of `the sha-lit by ineans ot afan or otherdraught inducingil ineans of ordinary type .and the Aair is drawn into the bottoni-of the shatt- `through holes `5811i the sides thereof.`

A solid Varin is shown in i-Figs. Sato l0 yot: the drawings, and this arin is. attached to Ltlicirablile slriatt L13, as` above described, and ilisiprovidedwithzairont :Flange SQand a rear flange 83 constructed as shown in the other views, so that the rabble teeth can be attached thereto, as shown in Fig. l of the drawing.

The passage at the side of the partition in the rabble arin through which the cooling inediuin is passed troni the rabble shaft can be provided at the entrance thereof with a transverse wall 50 (shown in dotted lines in Figures 5 and 6), havingl an opening` 50 the size ot which determines the aiiiount of cooling inediuin iloiiing from the shaft to the arin.

The difference in `the sizes of the openings 50 result in Va differential Circulation through the arms and thesizes of the said openings may therefore depend uponthe location of the arms within the furnace and the amount of cooling medium it is desired to pass tothe particular arm or arms.

In some cases it is found advantageous to prevent a circulation of cooling medium through one or more of the arms on a shaft and to cause a differential circulation of the cooling medium through the remaining arms and this is accomplished by blocking` the entrances 50 to the passages in the first mentioned arms and by providing openings of different sizes leading to the passages in the last mentioned arms.

The hereinbefore described improvements in the rabbling mechanism of ore roasting furnaces are applicable to straight line"7 and in some instances to turret multiple hearth furnaces and by the substitution, removal or addition of certain parts hereinbefore described different kinds and conditionsof work can be effectually performed and such arrangement of the parts as are most suitable to a particular requirement can be readily effected by any person skilled in the art.

l claim:

l. ln roasting furnaces, a hollow rabble shaft. having rabble arms detachably fitted thereto, partitions in the shaft and arms adapted to align with each other for governing the circulation of a cooling medium therethrough, means for supplying cooling medium to the shaft, means for effecting a ditlei'ei'itial circulation through the arms, tapered spigot and socket joints between the arms and shaft, slots in the arms, and tapered keys in the slots for drawinginto and maintaining in contact the tapered faces of the spigots and sockets to effect a water tight joint between the shaft and arms.

2. In roasting furnaces, a hollow rabble shaft having` a rabble arm fitted detachably thereto, a tapered spigot and socket joint between the arm and shaft, jaws on the inner end of the rabble arm adapted to engage the rabble shaft, and means for drawing into and maintaining in contact the tapered faces of the spigot and socket to effect a watertight joint between the said shaft and arm.

3. In roasting furnaces a hollow rabble shaft having a rabble arm fitted detachably thereto, a tapered spigot and socket joint between the inner end of the arm and the shaft, recesses in the sides of the shaft, aws on the inner ends of the arm adapted to slide in the recesses in the sides of the rabble shaft, and means for maintaining theI tapered faces of the spigot and socket tightly in contact.

el. In roasting furnaces a hollow rabble shaft having a rabble arm fitted detach-ably thereto, recesses in the sides of the rabble shaft, jaws on the inner end of the arm adapted to slide in the recesses in the rabble shaft, slots in the outer ends of the jaws, a cotter and gib passing through the said slots, and a recess in the back of the rabble shaft against the upper end of which the cotter is adapted to bear.

ln roasting furnaces a vertical hollow rabble shaft having an outwardly liared socket in the side wall thereof, a rabble arm having a tapered spigot on its inner end adapted to tit neatly in the flared socket, jaws on the inner end of the rabble arm on both sides of the spigot adapted to engage the rabble shaft, and a cotter for drawing the spigot tightly into the socket and for securely fastening the arm to the shaft.

(S. In roasting furnaces, a hollow rabbe shaft having a hole formed radially therein, a tapered spigot formed on the side wall of the shaft and surrounding the hole therein, a rabble arm having a tapered socket formed on the inner end thereof and adapted to tit neatly over the spigot, jaws on the inner end of the arm on both sides of the socket and adapted to engage the shaft, and a cotter for securely fastening the rabble arm on the shaft.

ln testimony whereof he has affixed his signature.

ARTHUR VICTOR LEGS-t). 

